topic Re: Where has the FPU gone??? in Kinetis Microcontrollers

Where has the FPU gone???

mjbcswitzerland — Tue, 25 Jul 2017 22:57:46 GMT

Hi All

Can anyone explain this?

- I have the FRDM-K66F board with the K66FN2M on it and a simple program that operates as normal.
- Then I have a new HW with a K66FX1M on it and am expecting the same code to run on it.

The new HW however hard faults when the FPU initialisation takes place (before any clock initialisation).

When I look at the default FPU system registers (after reset and before doing anything else) on the FRDM-K66F I see this

When I look at the registers on the new HW they are all at 0x00000000 and any code access to the registers is met with the hard fault.

So the question is, what can cause the FPU not to operate (normally) ???? I am expecting it to be to do with a HW connection (maybe a missing power pin?) since the prototype is hand built but there must be a logical explanation to aid in tracking down whatever it is.

Power supply is otherwise 3.3V exactly.

Regards

Mark

Re: Where has the FPU gone???

mjbcswitzerland — Wed, 26 Jul 2017 00:41:31 GMT

Curiouser and curioser.....

The ID on the FRDM-K66FN2M0 part is 0x660083ca, which means K66, rev. 8, 144-pins

The ID on the K66FX1M0 is 0x160083ff, which means K16, rev. 8 with reserved family ID and reserved pin count identification (there is no K16 that I can find).

If I configure the compiler to use SW FPU rather than the internal FPU the code runs on the K66FX1M0. However when I try to use the FS USB on it it hard faults on an USB access.
The reason being that, according to the SIM_SCGCx registers (which if one writes 0xffffffff to the bits that stick show the modules available) there is no USB0 in the chip. Also it shows no SDHC or FlexCAN1. No USBDCD, no RNGA, no FlexCAN0, no Ethernet.

On the package it is marked MK66FX1M0VLQ18, Mask 0N65N, batch OAK1712C - and it was originally delivered with the KBOOT loader programmed in Flash.

Is it possible that this is some form of dud (re-packaged reject?) that has been delivered?

Regards

Mark

Re: Where has the FPU gone???

Hui_Ma — Wed, 26 Jul 2017 05:24:06 GMT

Dear Mark,

Could you let us know which channel do you get that chip(MK66FX1M0VLQ18) from? NXP distributor or e-trader?

How many chips(MK66FX1M0VLQ18) do you have? If all with the same behavior?

The normal MK66FX1M0VLQ18 chip should provides SDHC, FlexCAN(2), USBDCD, Ethernet, RNGA, USB0 also.

I checked the MK66FX1M0VLQ18 sample in stock, could you use this link to apply for that chip samples?

Thank you for the attention.

Have a great day,
Ma Hui

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Re: Where has the FPU gone???

mjbcswitzerland — Wed, 26 Jul 2017 12:27:20 GMT

The chip was ordered here:
http://www.mouser.it/Search/ProductDetail.aspx?R=MK66FX1M0VLQ18virtualkey55700000virtualkey841-MK66FX1M0VLQ18

There is only one prototype available at the moment which I received from my client, but I have asked whether additional ones may be possible.

Regards

Mark

Re: Where has the FPU gone???

Hui_Ma — Thu, 27 Jul 2017 00:45:43 GMT

Hi Mark,

Please let us know if the other one still with the same issue. Thank you.

Have a great day,
Ma Hui

Re: Where has the FPU gone???

mjbcswitzerland — Wed, 09 Aug 2017 01:32:08 GMT

A second prototype has a chip from the same batch on it and it works normally (has FPU, USB0, FlexCAN etc.) and returns the expected ID.

Is there any possible explanation for the first one's behavior?

Regards

Mark

Re: Where has the FPU gone???

Hui_Ma — Thu, 10 Aug 2017 02:02:46 GMT

Hi Mark,

About the first one, I am checking with Kinetis product team.

I will let you know the feedback later. Thanks.

Have a great day,
Ma Hui